RainOfSteel
Explorer
How bad would it be if someone created two continuously connected portals, sent one into deep space, and dropped the other into the ocean?
How difficult would it be to do?
Do most of the realm worlds even have deep space?
I would say it depends on where in an ocean the source portal was dropped, in shallow water or in deep water, on a rocky bottom or mud, what kind of wildlife lived there, what kind of divinity or guardians were associated with the ocean, the portal's diameter, whether you consider the destination portal's structure to have a friction effect on the exiting ice, and we could go on and on.
Vibrations in the exiting ice column would, I think, cause it to break regularly. You would accumulate huge numbers of floating ice columns. They would exert very small gravitational fields on each other. After you had hundreds of thousands of them, you would have a giant mass of columns collected at the source portal, some floating free, some collected together in frozen palaces reminiscent of Superman's Fortress of Solitude. You could hypothesize that this would eventually plug the destination portal and stop any further drain and development.
Back at the source:
If the drain were going to affect the world seriously, the god of oceans/seas would take immediate interest. A giant rock slab, of the curiously unbreakable variety, could drop on the portal and shut it off. A hero could show up and disenchant it. Some desert dwellers learn of the destination portal, go and get it, and move it to their desert; water, water, everywhere!
The GM could decide that the immense pressure of water flowing through the portal created a destabilizing effect that eventually damaged the enchantment, that the immense weight of water at great depths crushed the portal into a twisted wreck, that a paragon whale got a little too close and became stuck in the portal, or anything.